The invention relates to a freight loading/unloading crane, in particular a container loading/unloading crane, comprising a crane bridge with two longitudinal ends arranged at a distance from each other in a transfer direction, where at least one lifting unit movable on the crane bridge in the transfer direction is associated with each of the longitudinal ends, said lifting unit containing at least one lifting system with associated load receiving means and a transfer unit containing a load receiving region with a load receiving area, where the transfer unit and the lifting units are designed such that loads can be exchanged between each of the lifting units and the transfer unit.
A freight loading/unloading crane of this type is known, for example, from German Patent No. 1,906,212. The known crane is used for the loading and unloading of container ships. For the unloading of a container ship, a first lifting unit, the so-called water or ship trolley, lifts a container from the cargo compartment of the ship and transfers it to a transfer unit movable on the crane bridge. Said transfer trolley transfers this container, on land, to a second lifting unit, the so-called land trolley, which then sets down the container on land while the transfer trolley returns to the first lifting trolley.
In the known container loading/unloading crane, the rendezvous maneuvers between the transfer trolley and land trolley proceed as follows: the transfer trolley usually reaches the land trolley before the latter has completely lifted its load receiving means, also referred to as "spreader" in container terminology. The transfer trolley must therefore brake and wait until the spreader has been completely lifted. The transfer trolley then moves under the land trolley, so that the latter can receive the container. However, in order for the land trolley to be then able to lower the container in the direction of the quay, the transfer trolley must first have again vacated the space under the land trolley.
To move the transfer trolley under the land trolley, the large mass of the transfer trolley, including the mass of the container, must be accelerated and then braked, and also, to vacate the space under the land trolley, the large mass of the transfer trolley must first be accelerated. The acceleration of this large mass takes time, which contributes to a lengthening of the operating cycle of the container loading/unloading crane.
The transfer trolley of the known container loading/unloading crane is therefore designed in such a way that the problems described above in a rendezvous of the transfer trolley and water trolley do not occur. However, the known solution can not be used simultaneously on the water and land sides.